Does the -Exchange2003Url need to resolve to a different public IP address than the 'standard' mail owa address. For example, I have mail.domain.com and legacy.domain.com pointing to the same public ip address (xxx.xxx.xxx.163).
Right now the public mail address is pointing to our Exchange 2003 server. Everything is working fine - I have only moved one test users to Exch 2010. When I point mail.domain.com to the Exch 2010 server, only the mailbox on the 2010 server can be accessed. It tries to redirect to legacy.domain.com and I get 404 file or directory not found.